The invention relates generally to watertight and airtight seals and, more particularly, to a sealing device for use at the interface of a bulkhead door assembly and a concrete foundation wall.
Basement or cellar doors have a long history of use for providing means for accessing a basement or cellar of a dwelling structure from the outside by way of a set of stairs. Since these basement or cellar spaces beneath the dwelling structure are located wholly or partly below ground level, they were usually damp and seldom occupied as living spaces. As such, there was generally not a requirement for eliminating air and water seepage around the edges of the door or where the door attached to the foundation wall of the dwelling structure.
Through the use of modem construction techniques, basements have been made more habitable by eliminating moisture incursion from the surrounding soil and reducing the loss of heat. This improvement enabled the use of basement spaces for additional living space, and typically provided for bedrooms and recreation areas. Furthermore, it is very economical to finish off these spaces. These "finished" basement spaces are normally accessed from the inside of the dwelling. However, most state building codes require that a second means of egress be provided from a basement in case of a fire. Today, approximately 90% of new homes built with a basement have bulkheads that are covered by a bulkhead door assembly. These bulkhead door assemblies are usually fabricated from sheet metal and have flanges that are between 11/4 and 11/2 inches wide for attaching the door assemblies to a top of a foundation wall.
Bulkhead door assemblies are prone to air and water leaks into the basements they are supposed to protect. The air and moisture causes damage to the door assembly and to the framing and structure of the house to which it is attached. The resulting problems include mold, mildew, and decay of the insulation and wood framing, as well as rust deterioration to the bulkhead door assembly itself. These problems often result from the manner in which the bulkhead door assembly is affixed to a foundation wall. The metal bulkhead door assembly is attached directly to the top of a concrete foundation wall by an attaching flange and is usually bolted down tight. The typical residential foundation wall is 10 inches thick, with about 61/2 inches of level concrete wall top exposed to weather on the outside of the door assembly. Because the top of the foundation wall is flat or concave, when it rains, the water sits on the top of the wall and wicks between the concrete and the metal bulkhead door assembly into the basement. Driving rain further enhances the water leakage, which usually occurs more on the front section than on the sides of the door assembly.
It is possible to partly solve the problem of water leakage around a bulkhead door assembly by sloping the top of the concrete wall away from the bulkhead mounting flange so that water would tend to drain off the top of the foundation wall. This is not a common practice because of the difficulty and expense of providing the slope at the desired location. Another proposed solution to the leakage problem is to apply a sealant, such as silicone, to the edges of the bulkhead door assembly attaching flange to prevent air and water leakage. This solution is only temporary because the metal door attaching flange expands and contracts with temperature excursions while the foundation wall retains essentially constant dimensions. This movement eventually causes the sealant to pull away from the metal attaching flange, creating a void in the interface allowing water and air to enter. The problem is compounded in colder climates where the water that has entered freezes, causing the void in the sealant to enlarge and allow more air and water to enter. Another problem is that the top of the concrete foundation wall is uneven and not perfectly straight and level. Thus, when the flat metal of the attaching flange is placed over the uneven concrete surface, there are numerous voids between the metal flange and the concrete. These voids allow water and air to enter into the inside of the bulkhead door assembly. Therefore, the leakage problem associated with basement door assemblies has become an important issue in finished basement spaces in modem house construction.
For the foregoing reasons, there is a need, therefore for a sealing device that allows a means for effectively sealing the interface between the mounting flange of a bulkhead door assembly and the top of a concrete foundation wall to which it is attached, in order to prevent air and water from intruding into basement spaces. This device must be inexpensive to manufacture, and must be capable of being easily installed at the construction site.